That makes good sense. Yobyot, just trying to stay clear of some of the murky and counterintuitive explanations I saw above.

I suspect the issues on abrupt cornering are more complex, and I do expect sometimes better performance with xDrive on the very steep hills near my house, especially with wet leaves, snow, and ice. Seattle occasionally gets shut down by sheets of ice, and some skiing is likely in the picture.

Another complication is that friction diminishes gradually, well before traction is lost (http://www.sciencedirect.com/science...43164808000847, not sure this link will work), so spreading the power across all the tires might be more beneficial than one might think from watching when clouds of smoked tires start to be visible.

It seems a little ironic, if I'm reading you right, that my milquetoasty driving has less use for the xDrive, while, if there's a benefit from your having the 1000 hp of an M Sport 335i, much more than my 328ix, it may well be when the "tires are turning to smoke", and the xDrive could be useful.